Novel photographic products and processes



April 5, 1969 s. YKASMAN ETA 3,438,775

NOVEL PHOTOGRAPHIC PRODUCTS AND PROCESSES F'led Au. l9 7 1 lo g 9 6 Sheet 1 of4 FCYAN DYE DEVELOP ER LAYER RED SENSITIVE SILVER HALIDE EMULSION LAYER P GREEN SENSITIVE SILVER HALIDE EMULSION LAYER INTERLAYER RJYELLOW DYE DEVELOPER LAYER Blue SENSITIVE SILVER HALIDE EMULSION LAYER Yh-OVERCOAT LAYER :31 \29 30 Aqueous ALKALINE PROCEssm /72| 29 r COMPOSITION g /////7 /7//// )-lMAGE-RECEN|NG LAYER SPACER LAYER 28 NE UTRALIZING LAYER SUPPORT 2g INVENTORS W 772. 39% ATTORNEYS April 15, 1969 Filed Aug. 9, 1967 INTEGRAL RED DENSITY s. KASMAN ETAL 3,438,775

NOVEL PHOTOGRAPHIC PRODUCTS AND PROCESSES Sheet 2 of 4 FIGQZ INVENTORS 28W xaAmLa/r i BY fiouwlwl "r i iwumwrwl amol W m. am ATTORNEYS lNTEGRAL RED DENSITY April 1969 s. KASMAN ETAL 3,438,775

NOVEL PHOTOGRAPHIC PRODUCTS AND PROCESSES Filed Aug. 9, 1967 Sheet 3 of 4 IMBIBITION (SECONDS) INVENTORS W 31M BY i lwwm a/nd and W m. Jozd ATTORNEYS 0 lb 26 3b 4b 6 0 7 0 I00 H0 I20 I30 I40 INTEGRAL GREEN DENSITY Apnl 15, 1969 s. KASMAN ETAL 3, 7

NOVEL PHOTOGRAPHIC PRODUCTS AND PROCESSES Filed Aug. 9, 1967 Sheet 4 of 4 A 2.o- L c M MW EL L8 0 IO so so 10 so I00 no I30 :40

IMBIBITION (SECONDS) INVENTORS QfW W BY flowwwl 5'1 612mm and 772M a/rwl 788M 772. 7nd

ATTORNEYS United States Patent 3,438,775 Patented Apr. 15, 1969 US. Cl. 963 21 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to photography and, more particularly, to photographic products which comprise a photosensitive silver halide emulsion having a dye which is a silver halide developing agent, i.e., a dye developer, associated therewith in a concentration within the range of about 0.01 to mgs. of dye per mg. of silver, by weight, dispersed in an alkaline solution permeable polymeric matrix in a concentration within the range of about 0.1 to 25 mgs. of dye per mg. of polymer, by weight, and in particulate form having a particle size distribution wherein at least and preferably at least 75% of the dye possesses a diameter below about 1 micron, and to photographic dye developer diffusion transfer processes particularly adapted to employ such products.

The primary objects of the present invention are to provide photographic products particularly adapted for employment in photographic diffusion transfer dye developer processes; to provide photographic products which comprise a photosensitive element which contains a plurality of essential layers including a dimensionally stable support layer carrying at least one photosensitive silver halide emulsion layer having associated therewith particulate dye, which is a silver halide developing agent and is soluble and diffusible in alkali, in a particle size distribution whereat at least 50%, and preferably at least 75% of the dye is below about 1 micron and, most preferably, below about 0.8 micron in diameter associated with said silver halide in a concentration range of about 0.01 to 5 mgs. of dye per mg. of silver, by weight, dispersed in an alkaline solution permeable polymeric matrix at a concentration within the range of about 0.1 to 25 mgs. of dye per mg. of polymer, by weight; to provide photographic diffusion transfer products comprising a photosensitive element, of the last-identified type, in combination with a photoinsensitive diffusion transfer imagereceiving element which contains a plurality of essential layers including a dimensionally stable support layer carrying an alkaline solution permeable polymeric layer dyeable by said dye and, most preferably, comprising a support layer carrying, in order, a polymeric acid layer containing sufficient acidifying groups to effect reduction, subsequent to substantial dye transfer image formation, of the element from a first pH at which the dye is soluble and diffusible to a second pH at which the dye is insoluble and nondiifusible, and an alkaline solution permeable polymeric layer dyeable by the dye; to provide photographic diffusion transfer products comprising a film unit including a photosensitive element and an imagereceiving element, of the last-identified types, in combination with a rupturable container retaining an alkaline processing composition having a pH at which the dye is soluble and diffusible; and to provide photographic diffusion transfer color processes particularly adapted to employ such products.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the several steps and the relation and order of one or more of such steps with respect to each of the others, and the product possessing the features, properties and the relation of elements which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings wherein:

FIGURE 1 is a diagrammatic enlarged cross-sectional view illustrating the association of elements comprising a film unit particularly adapted for the performance of a diffusion transfer process for the production of a multicolor transfer image according to the present invention, the thickness of the various materials being exaggerated;

FIG. 2 is a graphical representation of the transfer image density vs. imbibition time relationship of specified dye transfer image formation during the performance of a diffusion transfer process, for the production of a multichromatic transfer image according to the present invention, comparedwith that of a control diffusion transfer process, for the production of a multichromatic transfer image according to the conventionally employed procedure of the prior art; and

FIGS. 3 and 4 are graphical representations of the transfer image density vs. imbibition time relationship of dye transfer image formation, at specified processing tem peratures, during the performance of a diffusion transfer process, for the production of a monochromatic transfer image according to the present invention, at stated temperatures, compared with that of a control diffusion transfor process, for the production of a monochromatic transfer image according to a procedure of the prior art.

As disclosed in US. Patent No. 2,983,606, issued May 9, 1961, a photosensitive element containing a dye de veloper, that is, a dye which is a silver halide developing agent, and a silver halide emulsion may be exposed and wetted by a liquid processing composition, for example, by immersion, coating, spraying, flowing, etc., in the dark, and the exposed photosensitive element is superposed prior to, during, or after wetting, on a s-heetlike support element which may be utilized as an imagereceiving element. In a preferred embodiment, the liquid processing composition is applied to the photosensitive element in a substantially uniform layer as the photosensitive element is brought into superposed relationship with the image-receiving layer. The liquid processing composition, positioned intermediate the photosensitive element and the image-receiving layer, permeates the emulsion to initiate development of the latent image contained therein. The dye developer is immobilized or precipitated in exposed areas as a consequence of the development of the latent image. This immobilization is apparently, at least in part, due to a change in the solubility characteristics of the dye developer upon oxidation and especially as regards its solubility in alkaline solutions. It may also be due in part to a tanning effect on the emulsion by oxidized developing agent, and in part to a localized exhaustion of alkali as a result of development. In unexposed and partially exposed areas of the emulsion, the dye developer is unreacted and diffusible and thus provides an imagewise distribution of unoxidized dye developer dissolved in the liquid processing composition, as a function of the point-to-point degree of exposure of the silver halide emulsion. At least part of this image- Wise distribution of unoxidized dye developer is transferred, by imbibition, to a superposed image-receiving layer or element, said transfer substantially excluding oxidized dye developer. The image-receiving element receives a depthwise diffusion, from the developed emulsion, of un oxidized dye developer without appreciably disturbing the imagewise distribution thereof to provide the reversed or positive color image of the developed image. The image-receiving element may contain agents adapted to mordant or otherwise fix the diffused, unoxidized dye developer. If the color of the transferred dye developer is affected by changes in the pH of the image-receiving element, this pH may be adjusted in accordance with well-known technique to provide a pH affording the desired color. The desired positive image is revealed by stripping the image-receiving layer from the photosensitive element at the end of a suitable imbibition period.

The dye developers, as noted above, are compounds which contain, in the same molecule, both the chromophoric system of a dye and also a silver halide developing function. By a silver halide developing function is meant a grouping adapted to develop exposed silver halide. A preferred silver halide development function is a hydroquinonyl group. Other suitable developing functions include ortho-dihydroxyphenyl and orthoand paraamino substituted hydroxyphenyl groups. In general, the development function includes a benzenoid developing function, that is, an aromatic developing group which forms quinonoid or quinone substances when oxidized.

Multicolor images may be obtained using color imageforming components such as, for example, the previously mentioned dye developers, in diffusion transfer processes by several techniques. One such technique contemplates obtaining multicolor transfer images utilizing dye developers by employment of an integral multilayer photosensitive element, such as is disclosed in the aforementioned US Patent No. 2,983,606, and particularly with reference to FIG. 9 of the patents drawing, wherein at least two selectively sensitized photosensitive strata, superposed on a single support, are processed, simultaneously and without separation, with a single, common imagereceiving layer. A suitable arrangement of this type comprises a support carrying a red-sensitive silver halide emulsion stratum, a green-sensitive silver halide emulsion stratum and a blue-sensitive silver halide emulsion stratum, said emulsions having associated therewith, respectively, for example, a cyan dye developer, a magenta dye developer and a yellow dye developer. The dye developer may be utilized in the silver halide emulsion layer, for example, in the form of particles, or it may be employed as a layer behind the appropriate silver halide emulsion strata. Each set of silver halide emulsion and associated dye developer strata are disclosed to be optionally separated from other sets by suitable interlayers, for example, by a layer of gelatin or polyvinyl alcohol. In certain instances, it may be desirable to incorporate a yellow filter in front of the green-sensitive emulsion and such yellow filter may be incorporated in an interlayer. However, where desirable, a yellow dye developer of the appropriate spectral characteristics and present in a state capable of functioning as a yellow filter may be employed. In such instances, a separate yellow filter may be omitted.

The dye developers are preferably selected for their ability to provide colors that are useful in carrying out subtractive color photography, that is, the previously mentioned cyan, magenta and yellow.

As disclosed in copending US. application Ser. No. 234,864, filed Nov. 1, 1962 and now U.S. Patent No. 3,362,819, image-receiving elements, particularly adapted for employment in diffusion transfer processes of the type disclosed in aforementioned US. Patent No. 2,983,606, wherein the image-receiving elements are separated from contact with a superposed photosensitive element, subsequent to substantial transfer image formation, preferably comprise a support layer possessing on one surface thereof, in sequence, a polymeric acid layer and an image-receiving layer adapted to provide a visible image upon transfer to said layer of ditfusible dye image-forming substance, and most preferably include an inert timing or spacer layer intermediate the polymeric acid layer and the image-receiving layer.

As set forth in the last-mentioned application, the polymeric acid layer comprises polymers which contain acid groups, such as carboxylic acid and sulfonic acid groups, which are capable of forming salts with alkali metals, such as sodium, potassium, etc., or with organic bases, particularly quaternary ammonium bases, such as tetramethyl ammonium hydroxide, or potentially acid-yielding groups, such as anhydrides or lactones, or other groups which are capable of reacting with bases to capture and retain them. The acid-reacting group is, of course, non'diffusible from the acid polymer layer. In the preferred embodiments disclosed, the acid polymer contains free carboxyl groups and the transfer processing composition employed contains a large concentration of sodium and/or potassium ions. The acid polymers stated to be most useful are characterized by containing free carboxyl groups, being insoluble in water in the free acid form, and by forming water-soluble sodium and/ or potassium salts. One may also employ polymers containing carboxylic acid anhydride groups, at least some of which preferably have been converted to free carboxyl groups prior to imbibition. While the most readily available polymeric acids are derivatives of cellulose or of vinyl polymers, polymeric acids from other classes of polymers may be used. As examples of specific polymeric acids set forth in the application, mention may be made of dibasic acid half-ester derivatives of cellulose which derivatives contain free carboxyl groups, e.g., cellulose acetate hydrogen phthalate, cellulose acetate hydrogen glutarate, cellulose acetate hydrogen succinate, ethyl cellulose hydrogen succinate, ethyl cellulose acetate hydrogen succinate, cellulose acetate hydrogen succinate hydrogen phthalate; ether and ester derivatives of cellulose modified with sulfoanhydrides, e.g., with ortho sulfobenzoic anhydride; olystyrene sulfonic acid; carboxymethyl cellulose; polyvinyl hydrogen phthalate; polyvinyl acetate hydrogen phthalate; polyacrylic acid; acetals of polyvinyl alcohol with carboxyor sulfo-substituted aldehydes, e.g., 0-, m-, or p-benzaldehyde sulfonic acid or carboxylic acid; partial esters of ethylene/maleic anhydride copolymers; partial esters of methyl-vinyl ether/ maleic anhydride copolymers; etc.

The acid polymer layer is disclosed to contain at least sufiicient acid groups to effect a reduction in the pH of the image layer from a pH of about 13 to 14 to a pH of at least 11 or lower at the end of the imbibition period, and preferably to a pH of about 5 to 8 within a short time after imbibition. As previously noted, the pH of the processing composition preferably is of the order of at least 13 to 14.

It is, of course, necessary that the action of the polymeric acid be so controlled as not to interfere with either development of the negative or image transfer of unoXidized dye developers. For this reason, the pH of the image layer is kept at a level of pH 12 to 14 until the dye image has been formed after which the pH is reduced very rapidly to at least about pH 11, and preferably about pH 9 to 10, before the transfer image is separated and exposed to air. Unoxidized dye developers contaming hydroquinonyl developing radicals may diffuse from the negative to the positive as the sodium or other alkali salt. The diffusion rate of such dye image-forming components thus is at least partly a function of the alkali concentration, and it is necessary that the pH of th image layer remain on the order of 12 to 14 until transfer of the necessary quantity of dye has been accompllshed. The subsequent pH reduction, in addition to its desirable effect upon image light stability, serves a highly yaluable photographic function by substantially terminatmg further dye transfer. The processing technique thus effectively minimizes changes in color balance as a result of longer imbibition times in multicolor transfer processes using multilayer negatives. i

In order to prevent premature pH reduction during transfer processing, as evidenced, for example, by an undesired reduction in positive image density, the acid groups are disclosed to be so distributed in the acid polymer layer that the rate of their availability to the alkali is controllable, e.g., as a function of the rate of swelling of the polymer layer which rate in turn has a direct relationship to the diffusion rate of the alkali ions. The desired distribution of the acid groups in the acid polymer layer may be effected by mixing the acid polymer with a polymer free of acid groups, or lower in concentration of acid groups, and compatible therewith, or by using only the acid polymer but selecting one having a relatively lower proportion of acid groups. These embodiments are illustrated, respectively, in the cited copending application, by (a) a mixture of cellulose acetate and cellulose acetate hydrogen phthalate, and (b) a cellulose acetate hydrogen phthalate polymer having a much lower percentage of phthalyl groups than the first-mentioned cellulose acetate hydrogen phthalate.

It is also disclosed that the layer containing the polymeric acid may contain a water-insoluble polymer, preferably a cellulose ester, which acts to control or modulate the rate at which the alklai salt of the polymer acid is formed. As examples of cellulose esters contemplated for use, mention is made of cellulose acetate, cellulose acetate butyrate, etc. The particular polymers and combinations of polymers employed in any given embodiment are, of course, selected so as to have adequate wet and dry strength, and when necessary or desirable, suitable subcoats may be employed to help the various polymeric layers adhere to each other during storage and use.

The inert spacer layer of the aforementioned copending application, for example, an inert spacer layer comprising polyvinyl alcohol or gelatin, acts to time control the pH reduction by the polymeric acid layer. This timing is disclosed to be a function of the rate at which the alkali diffuses through the inert spacer layer. It was stated to have been found that the pH does not drop until the alkali has passed through the spacer layer, i.e., the pH is not reduced to any significant extent by the mere diffusion into the interlayer, but the pH drops quite rapidly once the alkali diffuses through the spacer layer.

As disclosed in the last-mentioned copending application Ser. No. 234,864, the presence of an inert spacer layer was found to be effective in evening out the various reaction rates over a wide range of temperatures, for example, by preventing premature pH reduction when imbibition is effected at temperatures above room temperature, for example, at 95 to 100 F. By providing an inert spacer layer, that application discloses that the rate at which alkali is available for capture in the polymeric acid layer becomes a function of the alkali diffusion rates.

However, as disclosed in copending US. application Ser. No. 447,100, filed Apr. 9, 1965 in the names of Leonard C. Farney, Howard G. Rogers and Richard W. Young and now abandoned, preferably the aforementioned rate at which the cations of the alkaline processing composition, i.e., alkali ions, are available for capture in the polymeric acid layer should be decreased with increasing transfer processing temperatures in order to provide diffusion transfer color processes relatively independent of positive transfer image variations over an extended range of ambient temperatures.

Specifically, it is there stated to have been found that the diffusion rate of alkali through a permeable inert polymeric spacer layer increases with increased processing temperature to the extent, for example, that at relatively high transfer processing temperatures, that is, transfer processing temperatures above approximately 80 F., a premature decearse in the pH of the transfer processing composition occurs due, at least in part, to the rapid diffusion of alkali from the dye transfer environment and its subsequent neutralization upon contact with the polymeric acid layer. This was stated to be especially true of alkali traversing an inert spacer layer possessing permeability to alkali optimized to be effective within the temperature range of optimum transfer processing. Conversely, at temperatures below the optimum transfer processing range, for example, tempeatures below approximately 40 F., the last-mentioned inert spacer layer was disclosed to provide an effective diffusion barrier timewise preventing effective traverse of the inert spacer layer by alkali having temperature depressed diffusion rates and to resulting maintenance of the transfer processing environments high pH for such an extended time interval as to facilitate formation of transfer image stain and its resultant degradation of the positive transfer images color definition.

It is further stated in the last-mentioned copending appllcation Ser. No. 447,100 to have been found, however, that if the inert spacer layer of the print-receiving element is replaced by a spacer layer which comprises a permeable polymeric layer containing a polymeric material exhibiting permeability inversely dependent on temperature, that is, a polymeric film-forming material which exhibits decreasing permeability to solubilized alkali derived cations such as alkali metal and quaternary ammonium ions under conditions of increasing temperature, that the positive transfer image defects resultant from the aforementioned overextended pH maintenance and/or premature pH reduction are obviated.

As examples of polymers which were disclosed to exhibit inverse temperaturedependent permeability to alkali, mention may be made of: hydroxypropyl polyvinyl alcohol, polyvinyl methyl ether, polyethylene oxide, polyvinyl oxazolidinone, hydroxypropyl methyl cellulose, isopropyl cellulose, partial acetals of polyvinyl alcohol such as partial polyvinyl butyral, partial polyvinyl formal, partial polyvinyl acetal, partial polyvinyl propional, and the like.

The last-mentioned specified acetals of polyvinyl were stated to generally comprise saturated aliphatic hydrocarbon chains of a molecular weight of at least 1000, preferably of about 1000 to 50,000, possessing a degree of acetalation within about 10 to 10 to 30%, 20 to 80%, and 10 to of the polyvinyl alcohols theoretical polymeric hydroxyl groups, respectively, and including mixed acetals where desired.

Where desired, a mixture of the polymers is to be employed, for example, a mixture of hydroxypropyl methyl cellulose and partial polyvinyl butyral.

As examples of materials, for use as the image-receiving layer, mention may be made of solution dyeable polymers such as nylons as, for example, N-methoxymethyl polyhexamethylene adipamide; partially hydrolyzed polyvinyl acetate; polyvinyl alcohol with or with out plasticizers; cellulose acetate with filler as, for example, one-half cellulose acetate and one-half oleic acid; gelatin; and other materials of a similar nature, Preferred materials comprise polyvinyl alcohol or gelatin containing a dye mordant such as poly-4-vinylpyridine, as disclosed in US. Patent No. 3,148,061, issued Sept. 8, 1964.

As disclosed in the previous citations, the liquid processing composition referred to for effecting multicolor diffusion transfer processes comprises at least an aqueous solution of an alkaline material, for example, diethylamine, sodium hydroxide or sodium carbonate and the like, and preferably possessing a pH in excess of 12, and most preferably includes a viscosity-increasing compound constituting a film-forming material of the type which, when the composition is spread and dried, forms a relatively firm and relatively stable film. The preferred film-forming materials disclosed comprise high molecular weight polymers such as polymeric water-soluble ethers which are inert to an alkaline solution such as, for example, a hydroxyethyl cellulose or sodium carboxymethyl cellulose. Additionally, film-forming materials or thickening agents whose ability to increase viscosity is substantially unaffected if left in solution for a long period of time are also disclosed to be capable of utilization. As stated, the film-forming material is preferably contained in the processing composition in such suitable quantities as to impart to the composition a viscosity in excess of 100 cps. at a temperature of approximately 24 C. and preferably in the order of 100,000 cps. to 200,000 cps. at that temperature.

As disclosed in the aforementioned US. Patent No. 2,983,606, the dye developers may be incorporated in the respecitve silver halide emulsion or, in the preferred embodiment, in a separate layer behind the respective silver halide emulsion. Specifically, the dye developer as disclosed may, for example, be in a coating or layer behind the respective silver halide emulsion and such layer of dye developer may be fabricated by use of a coating solution containing from about 0.5 to 8%, by weight, of the respective dye developer distributed in a film-forming natural, or synthetic, polymer, for example, gelatin, polyvinyl alcohol, and the like, adapted to be permeated by the chosen diffusion transfer fluid processing composition.

As specifically stated in the last cited patent, the dye developer, when utilized in the photosensitive layer, should be employed so that it possesses low covering power whereby it will exert negligible absorption of the light which is utilized to expose the photosensitive element and, accordingly, when incorporated in the photosensitive layer, will be disposed in relatively large particle sizes.

As disclosed in copending U.S. application Ser. No. 565,135, filed Feb. 13, 1956 and now US. Patent No. 3,345,135, integral multilayer photosensitive elements comprising at least two selectively sensitized photosensitive silver halide emulsion strata carried on a common support each having associated therewith a dye developer of predetermined color may employ one or more of the selected dye developers in the form of fine ground particles, of a sufficiently coarse nature as to possess a relatively low covering power, dispersed in, on or behind its associated emulsion stratum.

As specifically stated in the last cited application, a dye developer utilized in the form of fine particles of the desired relatively coarse nature is more slowly solubilized by a processing composition, i.e., an aqueous alkaline processing composition, than if the same dye were molecularly dispersed, and to thus possess the desired properties necessary for deferred dye diffusibility desired according to the applications disclosure.

In addition to the aforementioned direct dispersion of a particulate solid material in a polymeric, or colloidal, matrix, the preparation of the dye developer dispersion may also be obtained dissolving the dye in an appropriate solvent, or mixture of solvents, and the resultant solution distributed in the polymeric binder, with optional subsequent removal of the solvent, or solvents, employed, as, for example, by vaporization where the selected solvent, or solvents, possesses a sufficiently low boiling point or washing where the selected solvent, or solvents, possesses a sufficiently high differential solubility in the wash medium, for example, water, when measured against the solubility of the remaining composition components, and/ or obtained by dissolving both the polymeric binder and dye in a common solvent.

For further detailed treatment of solvent distribution systems of the types referred to above, and for an extensive compilation of the conventional solvents traditionally employed in the art to effect distribution of photographic color-providing materials in polymeric binder-s, specifically for the formation component layers of photographic film units, reference may be made to US. Patents Nos. 2,269,158; 2,322,027; 2,304,939; 2,304,940; 2,801,171; and the like.

It has now quite unexpectedly been discovered, however, that if the dye developer selected to provide the dye transfer image, by photographic diffusion transfer proc essing, is specifically utilized in the form of a particulate dispersion having a particle size distribution wherein at least 50% and preferably at least of the dye is below about 1 micron in diameter and, most preferably, below about 0.8 micron in diameter, associated with the silver halide emulsion in a concentration of about 0.01 to 5 mgs. of dye per mg. of silver, by weight, and dispersed in an alkaline solution permeable polymeric matrix in a concentration of about 0.1 to 25 mgs. of dye per mg. of polymer, by weight, then a significantly improved photosensitive element particularly adapted for the production of a dye transfer image by photographic diffusion transfer processing may be obtained.

Specifically, employment of the detailed photosensitive element possessing the specified combination of definitive physical parameters, in the hereinbefore described photographic diffusion transfer process, provides higher dye transfer image density per unit time, higher dye transfer image density per unit dye coverage, e.g., per mg./ft. of photosensitive element dye concentration, and greater diffusion transfer processing temperature latitude, when compared with photosensitive elements employing the above-described crystalloidal solvent systems of the prior art, and lower induction periods for initiation of the development of photoexposed silver halide, increased potential photographic process speed, and greater transfer image dye saturation, when compared with photosensitive elements employing the above-described particulate dispersion systems of the prior art, which utilize particles of a sufiiciently large size as to provide the stated desired deferred solubilization.

In a preferred embodiment of the present invention, the photosensitive element is specifically adapted to provide for the production of a multicolor dye transfer image and comprises a dimensionally stable support layer carrymg at least two selectively sensitized silver halide emulsion strata each having a dye developer material of predetermined color associated therewith soluble and diffusible, in alkali at a first pH. The preferred photoinsensitive image-receiving element comprises an alkaline solution permeable polymeric layer dyeable by the dye developer; an alkaline solution permeable polymeric acid layer contaming sufiicient acidifying groups to effect reduction, subsequent to substantial multicolor transfer dye image formation, of the image-receiving element from the first pH to a second pH at which the dye image-providing material is insoluble and nonditfusible; and the dimensionally stable transparent layer.

The silver halide emulsions comprising the multicolor photosensitive laminate preferably possess predominant spectral sensitivity to separate regions of the spectrum and each has associated therewith a dye, which is a silver halide developing agent and is, most preferably, substantially soluble in the reduced form only at the first pH, possessing a spectral absorption range substantially complementary to the predominant sensitivity range of its associated emulsion.

In the preferred embodiment, each of the emulsion strata, and its associated dye, is separated from the remaining emulsion strata, and their associated dye, by separate alkaline solution permeable polymeric interlayers and the dyeable polymeric layer is separated from the polymeric acid layer by an alkaline solution permeable polymeric spacer layer, most preferably a polymeric spacer layer having decreasing permeability to alkaline solution with increasing temperature.

In such preferred embodiment of the invention, the silver halide emulsion comprises photosensitive silver halide dispersed in gelatin and is about 0.6 to 6 microns in thickness; the dye itself is dispersed in an aqueous alkaline solution polymeric binder, preferably gelatin, as a separate layer about 1 to 7 microns in thickness; the alkaline solution permeable polymeric interlayers, preferably gelatin, are about 1 to 5 microns in thickness; the alkaline impermeable and about 2 to 6 mils in thickness. It will be specifically recognized that the relative dimensions recited above may be appropriately modified, in accordance with the desires of the operator, with respect to the specific product to be ultimately prepared.

In the preferred embodiment of the present inventions film unit for the production of a multicolor transfer image, the respective silver halide/ dye developer units of the photosensitive element will be in the form of a tripack configuration which will ordinarily comprise a cyan dye developer/red-sensitive emulsion unit contiguous the dimensionally stable support layer, the yellow dye developer/blue-sensitive emulsion unit most distant from the support layer and the magenta .dye developer/green-sensitive emulsion unit intermediate those units, recognizing that the relative order of such units may be varied in accordance with the desires of the operator.

Reference is now made to FIGURE 1 of the drawings wherein there is illustrated a preferred film unit of the present invention.

As illustrated in FIGURE 1, film unit 10 comprises rupturable container 11, retaining, prior to processing, aqueous alkaline solution 12, and photosensitive laminate 13 including, in order, dimensionally stable support layer 14, preferably a flexible sheet material; cyan dye developer layer 15; red-sensitive halide emulsion layer 16; interlayer 17; magenta dye developer layer 18; green-sensitive silver halide emulsion layer 19; interlayer 20; yellow dye developer layer 21; blue-sensitive silver halide emulsion layer 22; auxiliary layer 23, which may contain an auxiliary silver halide developing agent; and an image-receiving element 28 including image-receiving layer 24; spacer layer 25; neutralizing layer 26; and dimensionally stable support layer 27, preferably a flexible sheet material.

Rupturable container 11 may be of the type shown and described in any of US. Patent Nos, 2,543,181; 2,634,886; 2,653,732; 2,723,051; 3,056,492; 3,056,491; 3,152,515; and the like. In general, such containers will comprise a rectangular blank of fluidand air-impervious material folded longitudinally upon itself to form two walls 29 which are sealed to one another along their longitudinal and end margins to form a cavity in which processing solution 12 is retained. The longitudinal marginal seal 30 is made weaker than the end seals so as to become unsealed in response to the hydraulic pressure generated within the fluid contents 12 of the container by the application of compressive pressure to walls 29 of the container.

As illustrated in FIGURE 1, container 11 is fixedly positioned and extends transverse a leading edge of laminae 13 and 28 whereby to effect unidirectional discharge of the containers contents 12 between image-receiving layer 24 and the stated layer next adjacent thereto, upon application of compressive force to container 11. Thus, container 11, as illustrated, is positioned and extends transverse a leading edge of laminae 13 and 28 with its longitudinal marginal seal 30 directed toward the interface between image-receiving layer 28 and auxiliary layer 23. As previously mentioned, the fluid contents of the container comprise an aqueous alkaline solution having a pH at which the dye developers are soluble and diffusible.

In the performance of a diffusion transfer multicolor process employing film unit 10, the unit is exposed to radiation, actinic to photosensitive laminate 13.

Subsequent to exposure, film unit 10 is processed by being passed through opposed suitably gapped rolls in order to apply compressive pressure to frangible container 11 and to eflect rupture of longitudinal seal 30 and distribution of alkaline processing composition 12, having a pH at which the cyan, magenta and yellow dye developers are soluble and diffusible, intermediate dyeable polymeric layer 24 and auxiliary layer 23.

Alkaline processing solution 12 permeates emulsion layers 16, 19 and 22 to initiate development of the latent images contained in the respective emulsions. The cyan, magenta and yellow dye developers, of layers 15, 18 and 21, are immobilized, as a function of the development of their respective associated silver halide emulsions, preferably substantially as a result of their conversion from the reduced form to their relatively insoluble and nondiffusible oxidized form, thereby providing imagewise distributions of mobile, soluble and diifusible cyan, magenta and yellow dye developer, as a function of the point-to-point degree of their associated emulsions exposure. At least part of the imagewise distributions of mobile cyan, magenta and yellow dye developer transfers, by diffusion, to aqueous alkaline solution permeable polymeric layer 24 to provide a multicolor dye transfer image to that layer. Subsequent to substantial transfer image formation, a sufficient portion of the ions comprising aqueous alkaline solution 12 transfers, by diffusion, through permeable polymeric layer 24, permeable spacer layer 25 and to permeable polymeric acid layer 26 whereby alkaline solution 12 decreases in pH, as a function of neutralization, to a pH at which the cyan, magenta and yellow dye developers, in the reduced form, are insoluble and nondilfusible, to provide thereby a stable multicolor dye transfer image.

Subsequent to substantial transfer image formation, print-receiving element 28 may be manually dissociated from the remainder of the film unit, for example, by stripping.

The particulate dye developer dispersions possessing the stated particle size distribution, for employment in the practice of the present invention may be prepared by any of the conventional techniques, for example, ball mill, sand grinding, ultrasonic, and the like, for the production of particulate dispersions of solid materials which may be of irregular geometric shape, for example, present as more or less fragmented crystals, or the like.

It has been specifically ascertained, however, that an ultrasonic technique is particularly desirable for the preparation of solid dispersions from relatively small lots of dye developer, for example, lots comprising in the order of about 1 to 50 grams of dye, whereas a sand grinding technique is particularly desirable for preparation of solid dispersions from relatively large lots of dye, for example, 200+ grams of dye.

In general, a wet paste comprising solid dye developer particles and, optionally, one or more dispersing agents, surfactants, antifoamers, antioxidants, or the like, and water may be processed according to the identified techniques to provide dye developer particles of the size desired and the output of the process selected, Where desired, may be appropriately filtered to effect removal of any particles wihch may be present exceeding that of a diameter within the particle size range required.

Conventional sand grinding techniques adapted to mill solid dye developer particles such as to provide the requisite particle size distribution generally comprise agitating an aqueous dye developer slurry with a sand, which, for example, may possess a size range of 20 to 40 mesh, until the required particle size distribution is obtained and then separating the dye from contact with the a'brasive sand. Commercial mills, of various capacities, adapted to perform sand grinding may be procured from the Chicago Boiler Co., Chicago, Ill.

For the preparation of dye developer possessing the requisite particle size distribution by ultrasonic techniques, an aqueous dye developer slurry may be treated employing commercial sonifiers such as those procured from Branson Instruments, Inc., Stamford, Conn.

The present invention will be further illustrated and detailed in conjunction with the following specific examples which set out representative embodiments and photographic utilization of the novel photographic film units of this invention, which, however, are not limited to the details therein set forth and are intended to be illustrative only.

Film units similar to that shown in the drawing may be prepared as follows. A photosensitive element may be prepared, for example, by coating, in succession, on a gelatin subbed, opaque cellulose triacetate film base, the following layers:

(1) A layer of the cyan dye developer 1,4-bis-(p-[hydroquinonyl-a-methyl] ethyl-amino) 5,8 dihydroxyanth'raquinone having a particle size distribution wherein at least 75% of the dye possesses a diameter of less than 0.8 micron prepared by dissolving 1 gram, dry weight, of the dye in cc. of acetone; filtering the resultant solution to remove any acetone insolubles; precipitating the dye in 125 cc. of water; filtering the precipitate in a Buchner funnel; washing the filter cake with water; forming an aqueous slurry comprising -7% dye, by weight, and 2 to 15%, by weight of dye, of Lomar D [trade name of Nopco Chemical Co., Newark, N.]., for a surfactant comprising the sodium salt of a condensed mononaphthalene sulfonic acid], at a pH of -7 to 8; sonifying the slurry in a J17 Sonifier from Branson Instruments, Inc., Stamford, Conn., for 15+ minutes; and dispersed in gelatin and coated at a coverage of about 159 mgs./ft. of dye and about mgs./ft. of gelatin;

(2) A red-sensitive gelatino-silver iodobromide emulsion coated at a coverage of about 222 mgs./ft. of silver and about 142 mgs./ft. of gelatin;

(3) A layer of vinyl acetate-crotonic acid copolymer containing 2%, by weight, crotonic acid, coated at a coverage of about 135 mgs./ft.

(4) A layer of the magenta dye developer 2-(p-[p3-hydroquinonylethyl]-phenylazo) 4 isopropoxy-l-naphthol dissolved in N,N-diethyl decanamide, at a ratio of 1:2, dye to solvent (weight/volume), and dispersed in gelatin and coated at a coverage of 72 mgs/ft. of dye and about 108 mgs./ft. of gelatin;

(5) A green-sensitive gelatino-silver iodobromide emulsion coated at a coverage of about 108 mgs./ft. of silver and mgs./ft. of gelatin;

(6) A layer of gelatin coated at a coverage of about 104 mgs./ft.

(7) A layer of the yellow dye developer 4-(p[ 3-hydroquinonlyethyl1phenylazo) 3 (N-n-hexy1carboxamido)- 1-phenyl-5-pyrazolone dissolved in N,N-diethyl laurarnide, at a ratio of 1:1, dye to solvent (weight/volume), and dispersed in gelatin and coated at a coverage of about 61 mgs./ft. of dye and 77 mgs./ft. of gelatin;

(8) A blue-sensitive gelatino-silver iodobromide emulsion coated at a coverage of about 61 mgs./ft. of silver and about 46 mgs./ft. of gelatin; and

(9) A layer containing 4-methylphenyl hydroquinone dispersed in gelatin and coated at a coverage of about 10 mgs/ft. of 4-methylphenyl hydroquione in N,N-diethyl lauramide and about 30 mgs/ft. of gelatin.

The last-mentioned yellow and magenta dye developers are disclosed in US. Patent No. 3,134,764 and the cyan dye developer is disclosed in U.S. Patent No. 3,135,606.

A print-receiving element may be prepared, for example, by coating a cellulose nitrate subcoated baryta paper, in succession, with the following illustrative layers:

1) The partial butyl ester of polyethylene/maleic anhydride copolymer prepared by refluxing, for 14 hours, 300 grams of high viscosity poly-(ethylene/maleic anhydride), 140 grams of n-butyl alcohol and 1 cc. of phosphoric acid to provide a polymeric acid layer approximately 0.75 mil thick;

(2) An aqueous 4% solution of polyvinyl alcohol to provide a polymeric spacer layer approximately 0.3 mil thick; and

(3) A 2:1 mixture, by weight, of polyvinyl alcohol and poly-4-vinylpyridine, at a coverage of approximately 600 mgs./ft. to provide a polymeric image-receiving layer approximately 0.40 mil thick.

A rupturable container comprising, for example, an outer layer of lead foil and an inner liner or layer of polyvinyl chloride retaining an aqueous alkaline processing solution comprising, for example:

Water cc Potassium hydroxide grams 11.2 Hydroxyethyl cellulose (high viscosity), commercially available from Hercules Powder Co., Wilmington, Del., under the trade name Natrasol 250 grams 3.4 N-benzyl-a-picolinium bromide do 1.5 Benzotriazole do 1.0

may be affixed to the leading edge, of either element, such that upon application of compressive pressure to a container its contents are distributed, upon rupture of the containers marginal seal, between the surface layer of the photosensitive element and the polymeric imagereceiving layer of the image-receptive element.

The photosensitive element may then be exposed to actinic radiation and processed by passage of the exposed film unit through suitably gapped opposed rolls to effect rupture of the container and distribution of its processing composilion contents. After an imbibition period of, for example, about 1 minute, the image-receiving element may be separated from the remainder of the film assembly to reveal the resultant multicolor dye transfer image.

For purposes of comparison, an optimized photosensitive element may be fabricated in accordance wi h the last described procedure with the exception that layer 1 will comprise a layer of the identified cyan dye developer dissolved in N,N-diethyl decanamide, at a ratio of 1:2, dye to solvent (weight/volume), and dispersed in gelatin and coated at a coverage of 159 mgs./ft. of dye and 142 mgs./ft. of gelatin.

Employment of an illustrative test element and control element, prepared and processed as stated above, will provide the results set forth in FIG. 2 wherein there is denoted the positive transfer dye image densityirn'bibition time relationship of the respective elements. The solid line represents the dye image density-imbibition time relationship of a rest element prepared as above employing the stated solid dye dispersion of 1,4-bis-(fi- [hydroquinonyl a methyl]-ethy1-amino)-5,8-dihydroxyanthraquinone within the parameters detailed, and the broken line represents the dye image density-imbibition time relationship of a control element prepared employing the stated dye dissolved in the identified crystalloidal solvent according to the traditional procedures of the art. As is clearly indicated from examination of the test and control relationship set forth in FIG. 2, the present invention provides for the production of greater transfer image dye density per unit time and correspondingly will provide greater transfer dye image density per unit dye coverage, i.e., per mg./ft. of dye disposed in the photosensitive element.

For purposes of demonstrating the advantageous diffusion transfer processing temperature latitudes possible of achievement employing the present invention, test elements may be prepared, for example, by coating, in succession, on a gelatin subbed, opaque cellulose triacetate film base, a layer of the cyan dye developer solid dispersion last identified at a coverage of about 100 mgs./ft. of dye and about 25 mgs./ft. of gelatin, and an overcoat layer comprising about 400 mgs./ft. of gelatin.

Optimized comparative control elements may be prepared, for example, by coating, in succession, on the same base material, a layer of the same cyan dye developer dissolved in N,N-diethyl decanamide, at a ratio of 1:2, dye to solvent (weight/volume), at a coverage of about 13 100 mgs./ft. of dye and about 90 mgs./ft. of gelatin, and an overcoat layer comprising about 400 mgs./ft. of gelatin.

Exposing and processing a resultant test and a control element, as set forth above, at processing temperatures of 50 and 100 F., provides the dye image density-imbibition time relationships detailed in FIG. 3, wherein curves A and B represent test and control elements, respectively, processed at 100 F. and curves C and D represent test and control elements, respectively, processed at 50 F., and which results directly correlated with the relationship of the test and control elements of FIG. 2 processed at 75 F.

As denoted in FIG. 3, the advantages detailed with reference to FIG. 2 extend across the range of ambient processing temperatures to thereby establish the improved processing temperature latitude obtained by reason of the present invention.

The last detailed procedure may be repeated at processing temperatures of 50 and 100 F., for purposes of further illustration, employing test photosensitive elements prepared, for example, by coating, in succession, on a gelatin subbed, opaque cellulose triacetate film base a layer of the magenta dye developer A 528, 565; e=l9,800, 20,400

on the same base material, a layer of the same magenta dye developer dissolved in N,N-diethyl dec'anamide, at a ratio of 1:2, dye to solvent (weight/volume), at a coverage of about 125 mgsjft. of dye and about 187 mgs./ft. of gelatin, a green-sensitive gelatino-silver iodobromide emulsion coated at a coverage of 108 mgs./ft. of silver and 65 mgs./ft. of gelatin, and an overcoat layer comprising about 140 mgs./ft. of gelatin.

Processing, as set forth above, a test and control element at 50 and 100 F. processing temperatures, provides the dye image density-imbibition time relationships detailed in FIG. 4, wherein curves A and B represent test and control elements, respectively, processed at 100 F and curves C and D represent test and control elements, respectively, processed at 5 0 F.

Corresponding to FIG. 3, the relationships graphically denoted in FIG. 4 further detail the advantages provided by the present invention with respect to the improved processing temperature latitude obtained.

Particle size distributions wherein a majority of the dye particles are present in a size exceeding 1 micron in diameter fail to provide the advantageous results achieved employing the same dye within the parameters set forth herein as required. Employment of the dye in a particle size distribution exceeding that set forth provides a systern wherein the time interval required by an aqueous alkaline solvent to dissolve the particulate dye material is sufliciently excessive as to destroy the advantageous results detailed.

Although the preceding specific examples have been couched in terms of the employment of the gelatin binder for carrying the stated solid dye dispersions, it will be recognized that any natural or synthetic polymeric material permeable by the aqueous alkaline processing composition, nonsubstantive to the dye selected and photographically nondeleterious, may be employed, for example, polyvinyl alcohol or any one or more of the polymeric binders identified hereinbefore, in whole or in part as a replacement for the illustrated gelatin polymer.

During formulation of the stated solid dispersion, as illustrated here, it may be desirable to employ YB. surfactant, or antioxidant, or dispersing agent and/or antifoaming agent. Agents constituted to provide such properties are well known in the art and are readiy available from a plurality of conventional commercial sources.

Particularly desirable surfactants, however, have been found to include esters of aliphatic dibasic acids disclosed in U.S. Patent No. 2,028,091 and particularly aliphatic esters of sulphosuccinic acids disclosed in U.S. Patent No. 2,240,476; the condensation products of alkyl phenols and ethylene oxide disclosed in GT8 Report, PB6 3822 (1946), U.S. Department of Commerce; U.S. Patent No. 2,203,883 and U.S. Patent No. 2,083,482; aromatic naphthalene sulfonic acids disclosed in U.S. Patent No. 2,328,034; and the like.

The pH of the alkaline processing solution initially employed must be an alkaline pH at which the dye developers employed are soluble and dilfusible. Although it has been found that the specific pH to be employed may be readily determined empirically for any dye developer, or group of dye developers, most particularly desirable dye developers are soluble at pHs above 9 and relatively insoluble at pHs below 9, in reduced form, and relatively insoluble at substantially any alkaline pH, in oxidized form, and the system can be readily balanced accordingly for such dye developers. In addition, although as previously noted, the processing composition, in the preferred embodiment, will include the stated film-forming viscosity-increasing agent, or agents, to facilitate spreading of the composition and to provide maintenance of the spread composition as a structurally stable layer of the laminate, subsequent to distribution, it is not necessary that such agent be employed as a component of the composition. In the latter instance, however, it will be preferred that the concentration of solvent, that is, water, etc., comprising the composition be the minimum amount necessary to conduct the desired transfer process, in order not to adversely affect the structural integrity of the laminate and that the layers forming the laminate can readily accommodate and dissipate the solvent throughout during processing and drying without effecting undesirable dimensional changes in the layers forming the laminate.

It will be noted that the liquid processing composition employed may contain an auxiliary or accelerating developing agent, such as p-methylaminophenol, 2,4-diaminophenol, p-benzylaminophenol, hydroquinone, toluhydroquinone, phenylhydroquinone, 4-methy1phenylhydroquinone, etc. It is also contemplated to employ a plurality of auxiliary or accelerating developing agents, such as a 3-pyrazolidone developing agent and a benzenoid developing agent, as disclosed in U.S. Patent No. 3,039,869, issued June 19, 1962. As examples of suitable combinations of auxiliary developing agents, mention may be made of l-phenyl-E-pyrazolidone in combination with pbenzylaminophenol and 1-phenyl-3-pyrazolidone in combination with 2,S-bis-ethylenimino-hydroquinone. Such auxiliary developing agents may be employed in the liquid processing composition or they may be initially incorporated, at least in part, in any one or more of the silver halide emulsion strata, the strata containing the dye developers, the interlayers, the overcoat layer, the imagereceiving layer, or in any other auxiliary layer, or layers, of the film unit. It may be noted that at least a portion of the dye developer oxidized during development may be oxidized and immobilized as a result of a reaction, e.g., an energy-transfer reaction, with the oxidation product of an oxidized auxiliary developing agent, the latter developing agent being oxidized by the development of exposed silver halide. Such a reaction of oxidized developing agent with unoxidized dye developer would regenerate the auxiliary developing agent for further reaction with the exposed silver halide.

In addition, development may be effected in the presence of an onium compound, particularly a quaternary ammonium compound, in accordance with the processes disclosed in U.S. Patent No. 3,173,786, issued Mar. 16, 1965.

It will be apparent that the relative proportions of the agents of the diffusion transfer processing composition may be altered to suit the requirements of the operator. Thus, it is within the scope of this invention to modify the herein described developing compositions by the substitution of preservatives, alkalies, etc., other than those specifically mentioned, provided that the pH of the composition is initially at the pH required. When desirable, it is also contemplated to include, in the developing composition, components such as restrainers, accelerators, etc. Similarly, the concentration of various components may be varied over a wide range and when desirable adaptable components may be disposed in the photosensitive element, prior to exposure, in a separate permeable layer of the photosensitive element and/ or in the photosensitive emulsion.

The dimensionally stable support layers referred to may comprise any of various types of conventional opaque and transparent rigid or flexible materials, for example, glass, paper, metal, and polymeric films of both synthetic types and those derived from naturally occurring products. Suitable materials include alkaline solution impermeable materials such as polymethacrylic acid, methyl and ethyl esters; vinyl chloride polymers; polyvinyl acetal; polyamides such as nylon; polyesters such as polymeric films derived from ethylene glycol terephthalic acid; and cellulose derivatives such as cellulose acetate, triacetate, nitrate, propionate, butyrate, acetate-propionate, or acetate-butyrate. It will be recognized that one or more of the designated layers may not be required where the remaining layers are such as to provide the functions of these layers in the absence of same, for example, where the remaining layers provide the requisite dimensional stability properties.

In all examples of this specification, percentages of components are given by weight unless otherwise indicated.

An extensive compilation of specific dye developers particularly adapted for employment in photographic diffusion transfer processes is set forth in aforementioned U.S. Patent No. 2,983,606 and in the various copending U.S. applications referred to in that patent, especially in the table of U.S. applications incorporated by reference into the patent as detailed in column 27. As examples of additional U.S. patents detailing specific dye developers for photographic transfer process use, mention may also be made of U.S. Patents Nos. 2,983,605; 2,992,106; 3,047,386; 3,076,808; 3,076,820; 3,077,402; 3,126,280; 3,131,061; 3,134,762; 3,134,765; 3,135,604; 3,135,605; 3,135,606; 3,135,734; 3,141,772; 3,142,565; and the like.

As additional examples of synthetic, film-forming, permeable polymers particularly adapted to retain dispersed dye developer, mention may be made of nitrocarboxymethyl celluose, as disclosed in U.S. Patent No. 2,992,104;

an acylamidobenzene sulfo ester of a partial sulfobenzal of polyvinyl alcohol, as disclosed in U.S. Patent N0. 3,043,692; polymers of N-alkyl-a,e-t1nsaturated carboxamides and copolymers of N-alkyl-a,,8-carboxamides with N-hydroxyalk3 l-a,e-tinsatt1rated carboxamides, as disclosed in U.S. Patent No. 3,069,263; copolymers of vinylphthalimide and 0:,[3-111'1St1t1lfflt6d carboxylic acids, as disclosed in U.S. Patent No. 3,061,428; copolymers of N- vinylpyrrolidones and 06,5-11I1S3t11l'21t6d, carboxylic acids and terpolymers of N-vinyl-pyrrolidones, tarp-unsaturated carboxylic acids and alkyl esters of a,B-unsaturated carboxylic acids, as disclosed in U.S. Patent No. 3,044,873; copolymers of N,N-dialkyl-a,,B-unsaturated carboxamides with a,,8-unsaturated carboxylic acids, the corresponding amides of such acids, and copolymers of N-aryland N- cycloalkyl-a,fl-u1isaturated carboxamides with afi-unsaturated carboxylic acids, as disclosed in U.S. Patent No. 3,069,264; and the like.

For the production of the photosensitive gelatino silver halide emulsions employed to provide the film unit, the silver halide crystals may be prepared by reacting a watersoluble silver salt, such as silver nitrate, with at least one water-soluble halide, such as ammonium, potassium or sodium bromide, preferably together with a corresponding iodide, in an aqueous solution of a peptizing agent such as a colloidal gelatin solution; digesting the dispersion at an elevated temperature, to provide increased crystal growth; washing the resultant dispersion to remove undesirable reaction products and residual water-soluble salts by chilling the dispersion, noodling the set dispersion, and washing the noodles with cold water, or alternately, employing any of the various fiocc systems, or procedures, adapted to effect removal of undesired components, for example, the procedures described in U.S. Patents Nos. 2,614,928; 2,614,929; 2,728,662; and the like; after-ripening the dispersion at an elevated temperature in combination with the addition of gelatin and various adjuncts, for example, chemical sensitizing agents of U.S. Patents Nos. 1,574,944; 1,623,499; 2,410,689; 2,597,- 856; 2,597,915; 2,487,850; 2,518,698; 2,521,926; and the like; all according to the traditional procedures of the art, as described in Neblette, C. B., Photography Its Materials and Processes, 6th Ed., 1962.

Optical sensitization of the emulsions silver halide crystals may be accomplished by contact of the emulsion composition with an effective concentration of the selected optical sensitizing dyes dissolved in an appropriate dispersing solvent such as methanol, ethanol, acetone, water, and the like; all according to the traditional procedures of the art, as described in Hammer, F. M., The Cyanine Dyes and Related Compounds.

Additional optical additives, such as coating aids, hardeners, viscosity-increasing agents, stabilizers, preservatives, and the like, for example, those set forth hereinafter, also may be incorporated in the emulsion formulation, according to the conventional procedures known in the photographic emulsion manufacturing art.

The photoresponsive material of the photographic emulsion will, as previously described, preferably comprise a crystal of silver, for example, one or more of the silver halides such as silver chloride, silver iodide, silver bromide, or mixed silver halides such as silver chlorobromide or silver iodobromide, of varying halide ratios and varying silver concentrations.

The emulsions may include the various adjuncts, or addenda, according to the techniques disclosed in the art, such as speed-increasing compounds of the quaternary ammonium type, as described in U.S. Patents Nos. 2,271,- 623; 2,288,226; and 2,334,864; or of the polyethyleneglycol type, as described in U.S. Patent No. 2,708,162; or of the preceding combination, as described in U.S. Patent No. 2,886,437; or the thiopolymers, as described in U.S. Patents Nos. 3,046,129 and 3,046,134.

The emulsions may also be stabilized with the salts of the noble metals such as ruthenium, rhodium, palladium, iridium and platinum, as described in U.S. Patents Nos. 2,566,245 and 2,566,263; the mercury compounds of U.S. Patents Nos. 2,728,663; 2,728,664 and 2,728,665; the triazoles of U.S. Patent No. 2,444,608; the azindines of U.S. Patents Nos. 2,444,605; 2,444,606; 2,444,607; 2,450,397; 2,444,609; 2,713,541; 2,743,181; 2,716,062; 2,735,769; 2,756,147; 2,772,164; and those disclosed by Burr in Zwiss. Pot, volume 47, 1952, pages 228; the disulfides of Belgian Patent No. 569,317; the benzothiazolium compounds of U.S. Patents Nos. 2,131,038 and 2,694,716; and zinc and cadmium salts of U.S. Patent No. 2,839,405; and the mercapto compounds of U.S. Patent No. 2,819,965.

Hardening agents such as inorganic agents providing polyvalent metallic atoms, specifically polyvalent aluminum or chromium ions, for example, potash alum more coating aids, where desired and compatible, such as saponin; a polyethyleneglycol of U.S. Patent No. 2,831,- 766; a polyethyleneglycol ether of U.S. Patent No. 2,719,- 087, a taurine of U.S. Patent No. 2,739,891; a maleopalmitate of U.S. Patent No. 2,823,123; and amino acid of U.S. Patent No. 3,038,804; a sulfosuccinamate of U.S. Patent No. 2,992,108; or a polyether of U.S. Patent No. 2,600,831; or a gelatin plasticizer such as glycerin; a dihydroxyalkane of U.S. Patent No. 2,960,404; a bis-glycolic acid ester of U.S. Patent No. 2,904,434; a succinate of U.S. Patent No. 2,940,854; or a polymeric hydrosol of U.S. Patent No. 2,852,386.

As the binder for the respective imulsion strata, the aforementioned gelatin may be, in whole or in part, replaced with sorne other colloidal material such as albumin; casein; or zein; or resins such as a cellulose derivative, as described in U.S. Patents Nos. 2,322,085 and 2,327,808; polyacrylamides, as described in U.S. Patent No. 2,541,474; vinyl polymers such as described in U.S. Patents Nos. 2,253,078; 2,276,322; 2,276,323; 2,281,703;

2,484,456; 2,538,257; 2,579,016; 2,614,931; 2,624,674; 2,632,704; 2,642,420; 2,678,884; 2,691,582; 2,725,296; 2,753,264; and the like.

Although the precedng description of the invention has been couched in terms of the preferred photosensitive component construction wherein at least two selectively sensitized photosensitive strata are in contiguous coplanar relationship and, specifically, in terms of the preferred tripack type structure comprising a red-sensitive silver halide emulsion stratum, a green-sensitive silver halide emulsion stratum and a blue-sensitive silver halide emulsion stratum having associated therewith, respectively, a cyan dye developer, a magenta dye developer and a yellow dye developer, the photosensitive component of the film unit may comprise at least two sets of selectively sensitized minute photosensitive elements arranged in the form of a photosensitive screen wherein each of the minute photosensitive elements has associated therewith, for example, an appropriate dye developer in or behind its respective silver halide emulsion portion. In general, a suitable photosensitive screen will comprise minute red-sensitized emulsion elements, minute green-sensitized emulsion elements and minute blue-sensitized emulsion elements aranged in side-by-side relationship in a screen pattern and having associated therewith, respectively, a cyan, a magenta and a yellow dye developer.

The present invention also includes the employment of a black dye developer and the use of a mixture of dye developers adapted to provide a black and white transfer image, for example, the employment of dye developers of the three subtractive colors in an appropriate mixture in which the quantities of the dye developers are proportion such that the colors combine to provide black.

Where in the specification, the expression positive image has been used, this expression should not be in terpreted in a restrictive sense since it is used primarily for purposes of illustration, in that it defines the image produced on the image-carrying layer as being reversed, in the positive-negative sense, with respect to the image in the photosensitive emulsion layers. As an example of an alternative meaning for positive image, assume that the photosensitive element is exposed to actinic light through a negative transparency. In this case, the latent image in the photosensitive emulsion layers will be a positive and the dye image produced on the image-carrying layer will be negative. The expression positive image is intended to cover such an image produced on the imagecarrying layer.

In addition to the described essential layers, it will be recognized that the film unit may also contain one or more subcoats or layers, which, in turn, may contain one or more additives such as plasticizers, intermediate essential layers for the purpose, for example, of improving adhesion, and that any one or more of the described layers may comprise a composite of two or more strata of the same, or diiferent, components and which may be contiguous, or separated from, each other.

Since certain changes may be made in the above prodnot and process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. As a product, a photosensitive element which comprises, in combination, a support layer carrying a photosensitive silver halide emulsion having a dye, which dye is a silver halide developing agent, associated therewith in a concentration within the range of about 0.01 to 5 mgs. of dye per mg. of silver, by weight, dispersed in an alkaline solution permeable polymeric matrix in a concentration within the range of about 0.1 to 25 mgs. of dye per mg. of polymer, by weight, and in a particulate form having a particle size distribution wherein at least 50% of said dye is below about 1 micron in diameter.

2. As a product, a photosensitive element as defined in claim 1, wherein said dye is disposed in a separate layer intermediate said silver halide emulsion layer and said support.

3. As a product, a photosensitive element as defined in claim 1, wherein said dye is disposed in said silver halide emulsion layer.

4. As a product, a photosensitive element as defined in claim 1, wherein at least 75% of said dye is below about 0.8 micron in diameter.

5. As a product, a photosensitive element as defined in claim 1, wherein said photosensitive element comprises, in combination, a support layer carrying on one surface at least two selectively sensitized silver halide emulsion layers each having a dye, which dye is a silver halide developing agent, of predetermined color associated therewith, each of said dyes soluble and ditfusible, in alkali, at least one of said dyes being present in a concentration within the range of about 0.01 to 5 mgs. of dye per mg. of silver, by weight, dispersed in an alkaline solution permeable polymeric matrix in a concentration within the range of about 0.1 to 25 mgs. of dye per mg. of polymer, by weight, and in a particulate form having a particle size distribution wherein at least 75% of said dye is below about 1 micron in diameter.

6. As a product, a photosensitive element as defined in claim 5, wherein each of said selectively sensitized photosensitive silver halide emulsion layers has predominant spectral sensitivity to separate regions of the spectrum and the dye associated with each of said silver halide emulsion layers possesses a spectral absorption range substantially complementary to the predominant sensitivity range of its associated emulsion layer.

7. As a product, a photosensitive element as defined in claim 6, wherein at least one of said dyes is disposed in a separate alkaline solution permeable polymeric layer adjacent its associated silver halide emulsion layer, intermediate said emulsion layer and said support layer.

8. As a product, a photosensitive element as defined in claim 6, wherein each of said silver halide emulsion layers and its associated dye is separated from the next adjacent silver halide emulsion layer and its associated dye by an alkaline solution permeable polymeric interlayer.

9. As a product, a photographic film unit as defined in claim 5 including a diffusion transfer image-receiving element afiixed one edge of said photosensitive element, said diffusion transfer image-receiving element comprising, as essential layers, in sequence, a support layer, a polymeric acid layer, and a dyeable polymeric layer, said photosensitive and said image-receiving element adapted to be superposed with said silver halide emulsion, distal said support, positioned in overlying relationship with said dyeable polymeric layer.

10. As a'product, a photographic film unit as defined in claim 9 including a rupturable container retaining an aqueous alkaline processing composition having a pH at which said dye is soluble and diffusible afiixed one edge of one of said photosensitive and said image-receiving elements and adapted upon rupture to distribute its retained contents intermediate said photosensitive element and said image-receiving element upon superpositioning of said elements.

11. As a product, a photographic film unit as defined in claim 10, wherein said pH is not less than about 12.

12. As a product, a photosensitive element as defined in claim 6 including, as essential layers, in sequence, a common support layer, an alkaline solution permeable polymeric layer containing a cyan dye, a red-sensitive silver halide emulsion layer, an alkaline solution permeable polymeric layer containing magenta dye, a greensensitive silver halide emulsion layer, an alkaline solution permeable polymeric layer containing yellow dye, a bluesensitive silver halide emulsion layer, each of said cyan, magenta and yellow dyes being silver halide developing agents and being soluble and dilfusible, in alkali, at least one of said cyan, magenta and yellow dyes present in a concentration within the range of about 0.01 to 5 mgs. of dye per mg. of silver, by weight, dispersed in an alkaline solution permeable polymeric matrix in a concentration within the range of about 0.1 to mgs. of dye per mg. of polymer, by weight, and in a particulate form having a particle size distribution wherein at least 75% of said dye is below about 0.8 micron in diameter.

13. As a product, a photosensitive element as defined in claim 12, wherein said cyan dye is present in said particulate form and comprises 1,4-bis-(fi-[hydroquinonyl-amethyl]-ethylamino)-5,8-dihydroxy-anthraquinone.

14. A process of forming transfer images in color which comprises, in combination, the steps of exposing a photosensitive element which includes a support layer carrying a photosensitive silver halide emulsion having a dye, which dye is a silver halide developing agent, associated therewith in a concentration within the range of about 0.01 to 5 mgs. of dye per mg. of silver, by weight, dispersed in an alkaline solution permeable polymeric matrix in a concentration within the range of about 0.1 to 25 mgs. of dye per mg. of polymer, by weight, and in particulate form having a particle size distribution wherein at least 50% of said dye is below about 1 micron in diameter; contacting said exposed photosensitive element with an aqueous processing composition; effecting thereby development of the latent image contained in said silver halide emulsion; immobilizing the dye associated with said emulsion as a result of said development; forming thereby an imagewise distribution of mobile dye, as a function of the point-to-point degree of exposure; and transferring, by imbibition, at least a portion of said imagewise distribution of said mobile dye to a superposed image-receiving layer to provide thereto a dye image.

15. A process as defined in claim 14, wherein at least of said dye is below about 1 micron in diameter.

16. A process as defined in claim 15, wherein at least 75 of said dye is above about 0.8 micron in diameter. 17. A process of forming transfer images in color as defined in claim 15, which comprises, in combination, the steps of exposing a photosensitive element which includes a support layer carrying on one surface at least two selectively sensitized silver halide emulsion layers each having a dye, which dye is a silver halide developing agent, of predetermined color associated therewith, each of said dyes soluble and diffusible, in alkali, at least one of said dyes being present in a concentration within the range of about 0.01 to 5 mgs. of dye per mg. of silver, by weight, dispersed in an alkaline solution permeable polymeric matrix in a concentration within the range of about 0.1 to 25 mgs. of dye per mg. of polymer, by weight, and in particulate form having a particle size distribution wherein at least 75% of said dye is below about 1 micron in diameter; contacting said exposed photosensitive element with an aqueous processing composition; effecting thereby development of the latent images contained in each of said silver halide emulsions; immobilizing the dye associated with each of said emulsions as a result of said development; forming thereby an imagewise distribution of mobile dye, as a function of the point-to-point degree of exposure thereof; and transferring, by imbibition,

at least a portion of each of said imagewise distributions of mobile dye to a superposed image-receiving layer to provide thereto a multicolor dye image.

18. A process as defined in claim .17, wherein each of said selectively sensitized photosensitive silver halide emulsion layers has predominant spectral sensitivity to sep arate regions of the spectrum and the dye associated with each of said silver halide smulsion layers possesses a spectral absorption range substantially complementary to the predominant sensitivity range of its associated silver halide emulsion layer.

19. A process of forming a transfer image in color as defined in claim 17, which comprises, in combination, the steps of exposing a photosensitive element comprising at least two selectively sensitized silver halide emulsion strata, each of said silver halide emulsions having associated therewith a dye, which dye is a silver halide developing agent, of predetermined color, soluble and diffusible in alkali, at a first pH, at least one of said dyes being present in a concentration within the range of about 0.01 to 5 mgs. of dye per mg. of silver, by weight, dispersed in an alkaline tsolution permeable polymeric matrix in a concentration within the range of about 0.1 to 25 mgs. of dye per mg. of polymer, by weight, and in particulate form at a particle size distribution wherein at least 75 of said dye is below about 0.8 micron in diameter; applying an aqueous alkaline processing composition having said first pH to said photosensitive element; effecting thereby development of the latent image contained in each of said silver halide emulsions; immobilizing the dye associated with each of said emulsions as a result of said development; forming thereby an imagewise distribution of mobile dye, as a function of the point-topoint degree of exposure thereof; transferring, by imbibition, at least a portion of each of said imagewise distributions of mobile dye to a superposed image-receiving element which comprises, as essential layers, in sequence, an alkaline solution permeable and dyeable polymeric layer, an alkaline solution permeable polymeric acid layer and a support layer, to provide to said alkaline solution permeable and dyeable polymeric layer a dye image; and transferring, by imbibition, subsequent to substantial transfer dye image formation, a sufficient portion of the ions of said aqueous alkaline composition to said alkaline solution permeable polymeric acid layer to thereby reduce the alkalinity of said image-receiving element to a second pH at which said dyes are substantially insoluble and nondiffusible.

20. A process of forming a transfer image in color as defined in claim 18, which comprises, in combination, the steps of exposing a photosensitive element including bluesensitive, green-sensitive and red-sensitive gelatino silver halide emulsion layers mounted on a common support, said blue-sensitive, green-sensitive and red-sensitive silver halide emulsion la-yers having associated therewith, respectively, yellow, magenta and cyan dyes, each of said dyes being a silver halide developing agent soluble and diffusible in alkali, at a first pH, and being dispersed in a separate layer next adjacent its associated emulsion intermediate said emulsion and said support, at least one of said dyes being present in concentration within the range of about 0.01 to 5 mgs. of dye per mg. of silver, by weight, dispersed in an alkaline solution permeable polymeric matrix in a concentration Within the range of about 0.1 to 25 mgs. of dye per mg. of polymer, by weight, and in particulate form having a particle size distribution wherein at least 75% of said dye is below about 0.8 micron in diameter; contacting said exposed photosensitive element with an aqueous alkaline processing composition having said first pH; effecting thereby development of the latent image contained in each of said silver halide emulsions; immobilizing said yellow, magenta and cyan dye, as a functon of development of their respective associated silver halide emulsion; forming thereby an imagewise distribution of mobile yellow, magenta and cyan dye, as a function of the point-to-point degree of their respective associated silver halide emulsion; transferring, by diffusion, at least a portion of each of said imagewise distributions of mobile dye to a superposed image-receiving element which comprises an alkaline solution permeable and dyeable polymeric layer and an alkaline solution permeable polymeric acid layer mounted on a common support to provide to said alkaline solution permeable and dyeable polymeric layer a multicolor :dye image; and transferring, by diffusion, subsequent to substantial transfer image formation, a sufiicient portion of the ions of said aqueous alkaline composition to said alkaline solution permeable polymeric layer to thereby reduce the alkalinity of said image-receiving element to a second pH at which said dyes are substantially insoluble and nondifi'usible.

21. A process as defined in claim 20, wherein said cyan dye is present in said particulate form and comprises 1,4 bis-(fl-[hydroquinonyl-a-methyl]-ethylarnino) 5,8- dihydroxy-anthraquinone.

References Cited UNITED STATES PATENTS 2,977,390 8/1961 Land 963 3,345,163 10/1967 Land et al. 96-3 NORMAN G. TORCHIN, Primary Examiner. A. T. SUROPICO, Assistant Examiner.

US. Cl. X.R. 96--29, 77, 99 

